Neutral Network Assortativity Shapes Whether Selective Pressure Promotes or Hinders Robustness

Shorten, David and Nitschke, Geoff (2016) Neutral Network Assortativity Shapes Whether Selective Pressure Promotes or Hinders Robustness, Proceedings of IEEE Symposium Series on Computational Intelligence (IEEE SSCI 2016), Athens, Greece, 2370-2376, IEEE Press.

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Abstract

Due to the friendship paradox, the average robustness of the single mutation neighbours (µn) of genotypes on a neutral network is larger than the average robustness of the genotypes (µg). Random walks on neutral networks have an average degree equal to µn and, intuitively, we expect that evolution will not converge on populations whose average degree is considerably lower than this. This paper argues that a population achieving an average robustness higher than µn is facilitated by nodes of degree higher than µn being mutationally biased towards other nodes of degree higher than µn. Thus, we present the hypothesis that, for biologically realistic degree distributions, assortativity allows selection to increase robustness above µn. Furthermore, although counterexamples do exist, it is argued that it is highly plausible that in the majority of cases in which selection increases robustness above µn, that the neutral network is assortative. These arguments are reinforced by simulations of evolution on randomly generated Erdos-Renyi and power-law networks. Elucidating the role of assortativity provides valuable insight into the mechanisms by which robustness evolves as well as the conditions under which it will do so. Moreover, it demonstrates the large influence that higher-order mutational biases can have on evolutionary dynamics.

Item Type:	Conference paper
Subjects:	Computing methodologies > Modeling and simulation
Date Deposited:	23 Nov 2017
Last Modified:	10 Oct 2019 15:32
URI:	http://pubs.cs.uct.ac.za/id/eprint/1189

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